Wind turbines are continuously being designed and produced to be larger, to be more complex, and to have increased strength. One such structure is a wind turbine. Wind turbines can include a plurality of blades rotationally coupled to a generator rotor through a hub. The generator rotor can be mounted within a housing or nacelle, which may be positioned on top of a tubular tower or a base. The housing or nacelle has significant mass which is fatigue loaded on the tower or base. Movement of the housing due to wind or other forces may result in loads, such as reversing fatigue loads on the tower or base or on the nacelle or the housing.
Fatigue loaded structures or portions of structures may be subjected to numerous physical forces. Physical forces may result from factors including, but not limited to, environmental effects (such as sunlight being on only a portion of the structure at a time), operational effects, and/or exposure to changing conditions. For example, a wind turbine tower can sway due to changes in wind speed, thereby subjecting the tower to tensile and compressive forces on the metal structures making up the tower. The nacelle may be exposed to similar forces from the rotation of the blades. Likewise, a generator housing or other portions of the wind turbine can be subjected to these and other forces. Over time, the tensile and compressive forces can form cracks. Upon being formed, the cracks can propagate with continued cycling of tensile and compressive forces. Ultimately, the cracks can lead to failure of the structure.
To reduce, retard, or eliminate cracking, fillets having stress relief properties (for example, distribution of tensile and compressive forces) can be fastened to structures at locations where the structure is susceptible to cracking or experiences tensile and/or compressive forces.
Fillets used for stress relief require a significant amount of material and require significant labor to install.